Showing papers by "Edward T. Samulski published in 2016"

Search for microscopic and macroscopic biaxiality in the cybotactic nematic phase of new oxadiazole bent-core mesogens

Abstract: The possibility of biaxial orientational order in nematic liquid crystals is a subject of intense current interest. We explore the tendencies toward local and global biaxial ordering in the recently synthesized trimethylated oxadiazole-based bent-core mesogens with a pronounced asymmetric (bow-type) shape of molecules. The combination of x-ray diffraction and optical studies suggests that the biaxial order is expressed differently at the short- and long-range scales. Locally, at the scale of a few molecules, x-ray-diffraction data demonstrate biaxial packing. However, above the mesoscopic scale, the global orientational order in all three compounds is uniaxial, as evidenced by uniform homeotropic alignment of the nematic phase which is optically tested over the entire temperature range and by the observations of topological defects induced by individual and aggregated colloidal spheres in the nematic bulk.

Three-dimensional printing with build plates having surface topologies for increasing permeability and related methods

Abstract: A build plate (1300) for a three-dimensional printer includes: a rigid, optically transparent, gas-impermeable planar base (1310) having an upper surface and a lower surface; a flexible, optically transparent, gas-permeable sheet (1320) having an upper and lower surface, the sheet upper surface comprising a build surface for forming a three- dimensional object, the sheet lower surface positioned on the base upper surface; optionally, a channel layer (1311) between the planar base and the sheet; optionally, an adhesive layer (1314) between the planar base and the sheet; and wherein the build plate comprises a gas flow enhancing feature (114) configured to increase gas flow to the build surface, wherein one or more of sheet, the optional channel layer and the optional adhesive layer comprises the gas flow enhancing feature.

Build plates for continuous liquid interface printing having permeable base and adhesive for increasing permeability and related methods, systems and devices

Abstract: A build plate for a three-dimensional printer includes a rigid, optically transparent, gas-permeable planar base having an upper surface and an opposing lower surface; a gas permeable adhesive layer on the base upper surface; and a flexible, optically transparent, gas-permeable sheet having upper and lower surfaces, the upper surface comprising a build surface for forming a three-dimensional object, the sheet lower surface positioned on the adhesive layer opposite the base.

Three-dimensional printing with flexible build plates

Abstract: A build plate unit (400) for a three-dimensional printer includes a build plate (410) having an optically transparent member comprising a flexible, gas permeable, optically transparent sheet (414) having upper and lower opposing sides, wherein the flexible sheet upper side defines the build surface; and a flexible, gas permeable or impermeable, optically transparent base layer (412) on the lower side of the flexible sheet opposite the build region, wherein the build plate i s configured to permit gas flow to the build surface.

Build plates for continuous liquid interface printing having permeable sheets and related methods, systems and devices

Abstract: A build plate for a three-dimensional printer includes two or more flexible, optically transparent, gas-permeable sheets having upper and lower surfaces, the upper surface of a top one of the two or more gas-permeable sheets comprising a build surface for forming a three- dimensional object; and adhesive layers between each of the two or more sheets, wherein the two or more sheets and the adhesive layers together form a gas-permeable, rigid, optically transparent build plate that is configured to permit gas flow to the build surface.

Three-dimensional printing with reduced pressure build plate unit

Abstract: A method of forming a three-dimensional object, comprising: providing a carrier (18, 418) and an optically transparent member having a build surface, said carrier (18, 418) and said build surface defining a build region therebetween; filling said build region with a polymerizable liquid, continuously or intermittently irradiating said build region with light through said optically transparent member to form a solid polymer from said polymerizable liquid, continuously or intermittently advancing (e.g., sequentially or concurrently with said irradiating step) said carrier (18, 418) away from said build surface to form said three-dimensional object from said solid polymer, said optically transparent member comprising a flexible layer (414, 514, 614) having upper and lower opposing sides, wherein the flexible layer (414, 514, 614) upper side defines the build region, the method further comprising forming a region of reduced pressure adjacent the flexible layer (414, 514, 614) lower side.

Molecular ordering in the high-temperature nematic phase of an all-aromatic liquid crystal

Abstract: We report the structural characterization of the nematic phase of 2,6-biphenyl naphthalene (PPNPP). This lath-like all-aromatic mesogen provides a valuable benchmark for classical theories of nematic order. PPNPP exhibits a very high temperature nematic phase (417–489 °C) above an enantiotropic smectic A phase. X-ray diffraction reveals a surprisingly strong tendency towards molecular layering in the nematic phase, indicative of “normal cybotaxis” (i.e. SmA-like stratification within clusters of mesogens). Although stronger at low temperatures, the layering is evident well above the smectic A-nematic transition. The nematic order parameter is evaluated as a function of temperature from the broadening of the wide-angle diffuse diffraction feature. Measured values of the orientational order parameter are slightly larger than those predicted by the Maier–Saupe theory over the entire nematic range except for a narrow region just below the clearing point where they significantly drop below the theoretical prediction.

Three-Dimensional Printing Using Selectively Lockable Carriers

Abstract: A method includes: providing a three-dimensional printer including a build surface and a carrier that is movable away from and toward the build surface; advancing the carrier toward the build surface and contacting a lower surface of the carrier with the build surface or a fixture or frame member adjacent the build surface to align the carrier in an aligned position with the lower surface of the carrier parallel to the build surface; and locking the carrier in a locked state to maintain the carrier in the aligned position.

Continuous liquid interface production with sequential patterned exposure

Abstract: A method of forming the body portion of a three-dimensional object (17) from a polymerizable liquid (16) is carried out by a process including advancing a carrier (18) for the object away from a build surface while irradiating a build region between the carrier and build surface in a pattern of advancing and irradiating defined by an operating mode. The body portion has a plurality of contiguous segments, with the irradiating carried out in sequentially presented slices of exposure. Each slice having a pattern that corresponds to a segment of said body portion. Each pattern includesg regions of greater irradiation and regions of lesser irradiation (e.g., within the perimeter of each pattern). The method includes consecutively changing, for at least a portion of the forming of said three- dimensional object, the pattern between consecutive slices in a sequence of sequentially presented patterns of exposure that facilitates the flow of the polymerizable liquid to the build surface.

Build plate for three dimensional printing having a rough or patterned surface

Abstract: A build plate for a three dimensional printer comprising: a rigid, optically transparent, gas-impermeable planar base having upper and lower surfaces (710); and a flexible, optically transparent, gas-permeable sheet (720) having upper and lower surfaces, the upper surface comprising a build surface for forming a three dimensional object, the sheet lower surface being positioned on the base upper surface, wherein at least one of the base upper surface and the sheet lower surface has an uneven surface topology (712) that increases gas flow to the build surface.

Plaques de construction pour impression à interface liquide continue ayant des feuilles perméables et procédés, systèmes et dispositifs associés

Abstract: La presente invention concerne une plaque de construction pour une imprimante tridimensionnelle comprenant deux feuilles permeables aux gaz flexibles, optiquement transparentes ayant des surfaces superieure et inferieure, la surface superieure de l'une superieure des deux feuilles permeables aux gaz ou plus comprenant une surface de construction pour former un objet tridimensionnel; et des couches adhesives entre chacune des deux feuilles ou plus, les deux feuilles ou plus et des couches adhesives formant conjointement une plaque de construction permeable aux gaz, rigide, optiquement transparente qui est configuree pour permettre l'ecoulement de gaz vers la surface de construction.

Plaques de construction pour impression avec interface liquide continue comprenant une base perméable et un adhésif permettant d'augmenter la perméabilité, et procédés, systèmes et dispositifs associés

Abstract: L'invention concerne une plaque de construction pour une imprimante tridimensionnelle comprenant une base plane permeable aux gaz optiquement transparente et rigide dotee d'une surface superieure et d'une surface inferieure opposee ; une couche adhesive permeable au gaz sur la surface superieure de base ; et une feuille permeable au gaz optiquement transparent et souple presentant des surfaces superieure et inferieure, la surface superieure comprenant une surface de construction pour former un objet tridimensionnel, la surface inferieure de la feuille etant positionnee sur la couche adhesive opposee a la base.